1. Field of the Invention
The present invention relates to an apparatus and a method of diagnosing a motor used in driving a wheel of an electric vehicle and also to a self-diagnosing function of a drive motor.
2. Description of Related Art
In an electric vehicle, malfunction occurring in a motor, which is used to drive a vehicle, and/or a controller used to control the motor markedly affects the performance and safety. In particular, where the electric vehicle makes use of an in-wheel motor drive system, as a result of such device being planned to be downsized, a wheel bearing assembly, a reducer and a motor, all of which are parts of components of the in-wheel motor drive system, are subjected to a high speed operation and, therefore, securement of the reliability of those components is of a prime concern. In connection with the in-wheel motor drive system, suggestions have hitherto been made that in order to secure the reliability during the travel of the vehicle, temperatures of the wheel bearing assembly, the reducer and the motor or the like are measured to monitor the presence or absence of an overload so that in dependence of the temperatures measured, an electric drive current of the motor may be limited and/or the number of revolutions of the motor may be lowered. In this respect, see, for example, the patent document 1 listed below.